Serial communication Basic Wiring Method Gong Jianwei 2001.6.20 Distance: 1.DB9 and DB25 Common Signal Foot Description 2. RS232C Serial Port Communication Wiring Method 3. Some of the serial ports should be noted in serial port (DB9) And 25-pin serial port (DB25), the communication distance is closer (<12m), can be directly connected to the standard RS232 port (RS422, RS485 farther) with a cable, and the modem is required to attach the modem. The most simple and commonly used is three-line proceeds, that is, receive data and send data three-footed three-footed. This article only involves the most basic connection, and directly connects to RS232 to answer the front of the netizen. 1. Common signal foot description of DB9 and DB25
9-pin serial port (DB9) 25-pin serial port (DB25) needle number function Description abbreviation pin number function Description Abbreviation 1 Data carrier detection DCD 8 data carrier detection DCD2 Receive data RXD3 Receive data RXD 3 Send data TXD 2 Send data TXD 4 data terminal preparation DTR 20 Data Term Preparation DTR 5 Signal GND 7 Signal GND 6 Data Device Preparation DSR 6 Data Preparation DSR 7 Request Send RTS 4 Request Send RTS 8 Clear Send CTS 5 Clear Send CTS 9 Ring Indicator Dell 22 Ring Indication Dell
2. RS232C serial communication wiring method (three-wire system) First, the serial port transmission data can be implemented as long as there is reception data pin and the transmitting pin: the receiving pin of the same serial port is connected directly, and the two serial ports are connected or a serial port and Multiple serial ports
The receiving foot and send foot direct connection of the same serial port are connected to the 9-pin serial port and 25-pin serial port, all of which are directly connected to 3; two different serial ports (whether two serial ports of the same computer are different computers Serial port)
9-pin-9-pin 25-pin -25 needle 9-pin-25-pin 233222322333557757 The above table is for microcomputer standard serial port, there are many non-standard equipment, such as receiving GPS data or electronic compass data, as long as one principle : Receiving data pins (or lines) are connected to the transmitted data pin (or line), and the signal is connected to each other. 3. Some points should be noted in serial debugging:
Different coding mechanisms cannot be mixed, such as RS232C can't connect directly to the RS422 interface, specialized various converters on the market must be connected by the converter; the line welding should be firm, otherwise no problem, but because the line is misunderstood; When debugging, prepare a good debugging tool, such as serial debugging assistant, serial wizard, etc., there is a half-time effect; it is highly recommended not to charge the plug-in serial port. At least one end is powered off, otherwise the serial is easy to damage. The article is not finished, will be added with various serial ports 2001.6.20 Back to top
